1. Field of the Invention
The invention relates to an ink jet recording apparatus, and, more particularly, to an ink jet recording apparatus that stably ejects ink.
2. Description of the Related Art
In a known ink jet recording apparatus, such as a color ink jet printer, an ink tank that stores ink therein and an ink jet print head that ejects ink stored in the ink tank onto a recording medium are mounted on a carriage. The carriage mounting thereon the ink tank and the ink jet print head is reciprocated in a main scanning direction to perform printing onto the recording medium. Such color ink jet printer performs a purge operation which is generally performed to remove air in an ink passage in order to prepare the print head for printing when an ink tank is mounted on an ink jet printer, as well as to remove dried ink or foreign materials clogging nozzles of the print head and causing improper ink ejection. When the purge operation is performed in the latter case using a relatively strong suction force, air existing above the level of the ink in the ink tank might be sucked along with the ink, especially when an amount of the ink in the ink tank is small.
When the purge operation is performed, a substantially box-shaped purge cap makes contact with the ink ejection surface of the ink jet print head having the nozzles thereon, forming an enclosed space. Pressures in the enclosed space are reduced using a suction pump connected to the purge cap. The high viscous ink or air is sucked from the nozzles and discharged from a discharge port formed on the purge cap.
The suction pump used in a known ink jet printer for the purge operation is controlled such that the high viscous ink or air is sucked with relatively strong suction force, to recover from relatively poor ink ejection conditions. If the high viscous ink or air is sucked with such strong force when only a small amount of ink is present in the ink tank, that is, when considerable amount of air is contained in the ink tank, the air in the ink tank may be sucked by the strong force of the suction pump toward the ink jet print head. This may cause unstable ink ejection in a subsequent print operation.
An ink jet recording apparatus disclosed in, for example, Japanese Patent Publication No. 2,564,833 includes a detector that detects a condition that ink in an ink tank is about to run out and outputs a signal indicating such condition. After the detector outputs the signal, a purge command signal is not output to a controller that carries out a purge operation. In this case, however, the ink tank has to be replaced even though the ink tank has some ink left therein.
Accordingly, one aspect of the invention is to provide an ink jet recording apparatus that performs a purge operation without drawing air into an ink jet print head and that continues a print operation even when an amount of ink remaining in an ink tank is small in order to extend the life of the ink tank.
An ink jet recording apparatus according to the invention may include an ink tank that stores ink, an ink jet print head that performs recording onto a recording medium by ejecting the ink stored in the ink tank, the ink jet print head having an ink ejection surface on which nozzles are formed, a purge device that recovers an ink ejection condition by sucking the ink from the nozzles formed on the ink ejection surface, a remaining ink amount detection device that detects a remaining ink amount in the ink tank, and a suction force changing device that changes an ink suction force of the purge device according to the remaining ink amount detected by the remaining ink amount detection device.
In one aspect, the ink jet recording apparatus of the present invention may change the ink suction force of the purge device according to the remaining ink amount, so that a proper ink ejection condition may be restored with a relatively low ink suction force.